Question

我正在尝试找到一种方法来关闭持有我正在创建的pdf文件的进程。我试图在创建流之后处理和关闭流，但是我收到消息：进程无法访问文件'\ server \ PDFs \ test.pdf'，因为它正由另一个进程使用。基本上，一旦test.pdf最初创建，我就有了一个页面，他们可以编辑数据并重新创建一个修改过的test.pdf。知道如何关闭这个过程吗？我尝试做一个while语句循环来继续尝试但没有运气？

'Create the original pdf
 Dim pdfWrite As PdfWriter = PdfWriter.GetInstance(Doc1, New FileStream(path & myUniqueFileName, FileMode.Create))

    Doc1.Open()
    Dim test As String
    test = Session("PDF")
    Dim PDFHeader As String
    PDFHeader = Session("Header")
    Dim imagepath As String = Server.MapPath(".") & "/images/Header.png"
    Dim image As iTextSharp.text.Image = iTextSharp.text.Image.GetInstance(imagepath)
    image.ScalePercent(70.0F)
    Dim line1 As New iTextSharp.text.pdf.draw.LineSeparator(0.0F, 100.0F, BaseColor.BLACK, Element.ALIGN_LEFT, 1)

    Doc1.Add(image)
    Doc1.Add(New Paragraph(PDFHeader))
    Doc1.Add(New Chunk(line1))
    Doc1.Add(New Paragraph(test))
    pdfWrite.Flush()
    Doc1.Close()
    Doc1.Dispose()
    pdfWrite.Dispose()
    pdfWrite.Close()

编辑数据后重新创建pdf：

 Dim _fileInUse As Boolean = True
    Do While _fileInUse
        _fileInUse = FileInUse(myUniqueFileName)
        If Not _fileInUse Then
            Dim pdfWrite As PdfWriter = PdfWriter.GetInstance(Doc1, New FileStream(path & myUniqueFileName, FileMode.Create))


            Doc1.Open()
            Dim test As String
            test = Session("PDF")
            Dim PDFHeader As String
            PDFHeader = Session("Header")
            Dim imagepath As String = Server.MapPath(".") & "/images/Header.png"
            Dim image As iTextSharp.text.Image = iTextSharp.text.Image.GetInstance(imagepath)
            image.ScalePercent(70.0F)
            Dim line1 As New iTextSharp.text.pdf.draw.LineSeparator(0.0F, 100.0F, BaseColor.BLACK, Element.ALIGN_LEFT, 1)

            Doc1.Add(image)
            Doc1.Add(New Paragraph(PDFHeader))
            Doc1.Add(New Chunk(line1))
            Doc1.Add(New Paragraph(test))
        End If
    Loop



    Doc1.Close()
    Doc1.Dispose()

Public Function FileInUse(ByVal sFile As String) As Boolean

    Dim thisFileInUse As Boolean = False
    Dim fs As FileStream

    If File.Exists(sFile) Then
        Try
            fs = File.Open(sFile, FileMode.Open, FileAccess.Write, FileShare.ReadWrite)

            fs.Close()
            fs.Dispose()
        Catch
            Try
                fs.Close()
                fs.Dispose()
            Catch

            End Try

            thisFileInUse = True
        End Try
    End If
    Return thisFileInUse
End Function

Answer 1

New FileStream中有Dim pdfWrite As PdfWriter =...无法关闭它。

我建议你使用Using构造来处理你的事情，并利用Try..Catch中的Finally子句，如下所示：

Sub X()
    'Create the original pdf
    Using doc1 As New Document
        Dim myFile As String = Path.Combine(myPath, myUniqueFileName)
        Using fs As New FileStream(myFile, FileMode.Create)
            Using pdfWrite As PdfWriter = PdfWriter.GetInstance(doc1, fs)

                doc1.Open()
                Dim test As String
                test = Session("PDF")
                Dim PDFHeader As String
                PDFHeader = Session("Header")
                Dim imagepath As String = Server.MapPath("./images/Header.png")
                Dim image As iTextSharp.text.Image = iTextSharp.text.Image.GetInstance(imagepath)
                image.ScalePercent(70.0F)
                Dim line1 As New iTextSharp.text.pdf.draw.LineSeparator(0.0F, 100.0F, BaseColor.BLACK, Element.ALIGN_LEFT, 1)

                doc1.Add(image)
                doc1.Add(New Paragraph(PDFHeader))
                doc1.Add(New Chunk(line1))
                doc1.Add(New Paragraph(test))
                pdfWrite.Flush()

            End Using
        End Using
    End Using

End Sub

Public Function FileInUse(ByVal sFile As String) As Boolean

    Dim thisFileInUse As Boolean = False

    If File.Exists(sFile) Then
        Dim fs As FileStream = Nothing
        Try
            fs = File.Open(sFile, FileMode.Open, FileAccess.Write, FileShare.None)
        Catch
            thisFileInUse = True
        Finally
            If fs IsNot Nothing Then
                fs.Dispose()
            End If
        End Try
    End If

    Return thisFileInUse

End Function

Try..Catch的Last部分始终运行。

编辑：您当然会检查一个Class实例上的.Dispose（）方法是否会处理需要完成的任何家务，例如我检查{{3在没有做一个明确的.Close（）之前。我没有提供ITextSharp方法的文档，所以你必须自己检查一下。

Answer 2

你能不能只创建一个具有唯一名称的文件并更新它。我没有尝试过，但我不喜欢不断尝试在循环中打开文件以检查是否可以写入文件。也许这会导致问题

这样的东西？：

'Create the original pdf
Dim pdfWrite As PdfWriter = PdfWriter.GetInstance(Doc1, New FileStream(path &          myUniqueFileName, FileMode.Create))
Dim rdm As New Random()
Dim newName As String
newName =  myUniqueFileName + rdm.Next(0, 100000).ToString("00000")

Dim pdfWrite As PdfWriter = PdfWriter.GetInstance(Doc1, New FileStream(path & newName , FileMode.Create))
Doc1.Open()
Dim test As String
test = Session("PDF")
Dim PDFHeader As String
PDFHeader = Session("Header")
Dim imagepath As String = Server.MapPath(".") & "/images/Header.png"
Dim image As iTextSharp.text.Image = iTextSharp.text.Image.GetInstance(imagepath)
        image.ScalePercent(70.0F)
Dim line1 As New iTextSharp.text.pdf.draw.LineSeparator(0.0F, 100.0F, BaseColor.BLACK, Element.ALIGN_LEFT, 1)

Doc1.Add(image)
Doc1.Add(New Paragraph(PDFHeader))
Doc1.Add(New Chunk(line1))
Doc1.Add(New Paragraph(test))

Doc1.Close()
Doc1.Dispose()

无法关闭文件，被另一个进程使用

2 个答案: